Add body classes via template.php

function phptemplate_body_class($left, $right) {
  if ($left != '' && $right != '')
  {
    $class = 'sidebars';
  }
  else
  {
    if ($left != '')
    {
      $class = 'sidebar-left';
    }
    if ($right != '')
    {
      $class = 'sidebar-right';
    }
  }
 
  if (isset($class) && arg(0) == 'admin')
  {
    $class .= " admin";
  }
  elseif (arg(0) == 'admin')
  {
    $class = "admin";
  }
 
  if (isset($class))
  {
    print ' class="' . $class . '"';
  }
}